Personally, I'd go 7 or 8' 3 pt PTO.
Plenty of power to cut the big stuff, and will do decent on shorter stuff. It's not a grooming mower, so if you want it to look like the lawn, it ain't going to happen.
I use mine (Woods 7' PTO, 3 pt mount) to mow up to 3 feet tall grass, and to mow waterways down to about 3inches tall.
If I don't let it get too big (less than 12"), does a nice job. Just not a lawn mower. It will bunch up in the really tall, thick, heavy stuff, but that's to be expected.
Plus I think it would be hard doing a level job with FEL mount.
my 2 cents, again